TULSA, Okla. -- With his lone block of the game, Arizona sophomore Derrick Williams swatted away the University of Memphis' hopes of stunning the No. 5 seed Wildcats and moving on to the third round of the NCAA Tournament.

The block came after Tigers freshman guard Joe Jackson intentionally missed his second of two free throws with five seconds left and Memphis trailing Arizona by two points.

Memphis freshman Chris Crawford tapped the rebound over to Wesley Witherspoon, who went straight up from the left block with two seconds remaining.

Though Witherspoon appeared open for a moment, the 6-8, 241-pound Williams, the Pac-10 Player of the Year, stuffed his putback attempt to give Arizona a thrilling 77-75 second-round West Region victory Friday at the BOK Center, ending the Tigers' season.

"It was up for grabs and I went up and grabbed it, and the rest is history," said Witherspoon, hanging his head in the locker room. "When I got the ball, it was a basketball play, and Derrick Williams made a play on the ball."

No. 12 seed Memphis (25-10) trailed by five points with 53.1 seconds to play. But as it had done all season in close games, this Tigers team that relied so heavily on freshmen gave itself a chance to win down the stretch.

After Arizona freshman Jordin Mayes' two free throws gave the Wildcats (28-7) a 73-68 lead, Will Barton scored in the lane 15 seconds later to bring Memphis to three points.

A possession later, after a pair of Jamelle Horne free throws with 23.7 seconds left, Jackson answered with two more free throws.

Then Barton, whose Tigers had been 13-1 entering Friday's contest in games decided by five points or fewer, stole the inbounds pass.

His potential tying 3-pointer missed, but Jackson was there to clean it up, slicing Arizona's lead to 75-74 with a put-back underneath the basket with 12 seconds left.

"We've been in this situation plenty of times this year. We've been down at the last second and we had pulled through," said Barton's brother, Antonio, whose 17 points led four Memphis players in double figures. "We just always have hope that we're going to pull the game out."

Trailing 77-74 after another pair of free throws by Arizona, Jackson was fouled purposely with five seconds left to prevent Memphis from getting off a potential tying 3-pointer, setting up the final dramatic sequence.

"All I saw was Derrick Williams' block. I chased it down and that was that," said Horne, whose Wildcats advanced to play Texas on Sunday in the third round.

Although it was an agonizing way for Memphis to wrap up its season, coach Josh Pastner said this loss didn't make him as sick physically as the Tigers' other nine this season.

Although the Tigers had led by as many as 10 points in the first half, they never allowed Arizona to take control, fighting back from a 48-40 deficit early in the second half to take a five-point lead twice over the final 13:16.

"The guys battled," Pastner said. "As I told our guys, I don't feel sick to my stomach because all you can ask for is a chance to win the game. We played hard enough and competed hard enough that we gave ourselves an opportunity to win the game.

"So I have no regrets. I told the guys to keep their heads up. Overall, I was very proud of our young men the way they competed and battled because we had a shot, and that's all you can ask for."

The back-and-forth game featured 14 lead changes and four ties. After Memphis took a 21-11 lead midway through the first half, Arizona, which got a total of 22 points and 10 rebounds from Williams, responded with a 24-9 run over the next eight minutes and took a 41-37 lead into halftime.

Jones added 18 points for Arizona, and had a key timeout with 33 seconds left and Arizona leading by three. Memphis had appeared to tie Jones up on the floor, but officials ruled he had called a timeout. Ten seconds later, Horne made it a five-point game with his pair of free throws.

Will Barton had 12 points for Memphis, and Jackson and Witherspoon each had 10 off the bench. Memphis out-rebounded the Wildcats 33-29 and outscored them 24-12 in the paint in the second half, but it wasn't enough against an Arizona squad that seemed to make every key free throw down the stretch. The Wildcats finished 26-of-31 (83.9 percent) from the line.

"I'm so proud of my guys. I mean, with what Wesley went through -- people bashing him and calling him soft. Look at the effort he gave," Will Barton said of Witherspoon's defensive performance against Williams. "People bashing our freshmen. Look how we played. We didn't look like freshmen.

"Everybody who got in gave it their all, and even with all that said, I'm still sick because we should've won that game."